Abstract: Rock drill bit having shaving cutters on the leading end of a removable bit head for shaving the hole bottom and shaving reamer cutters extending lengthwise of the bit. The cutters and receiving slots therefor have dovetail configurations for trapping the cutters in the slots. Wedges for locating the cutters are disposed in the bottoms of the slots. Lateral passages communicate with a central mud passage to deliver mud fluid to ports between the cutters. The central mud passage has a venturi configuration and lengthwise extending passages in the bit extend downwardly from upstream of the venturi to intersect or communicate with the lateral passages. A core shaver is mounted by a collet chuck in the central passage close to its outlet to the leading end of the bit to shave a core formed on the hole bottom between the inner ends of the shaving cutters on the end face.

Abstract: A self renewing working tip tool characterized by a plurality of working tip surfaces on individual laminae assembled in nested relation. The laminae are of hardened steel and each has a hard metal carbide coating thereon. A series of such laminae are bonded together and secured to a suitable tool shank to form a tool useful in breaking concrete, mining coal, and the like, where a hard working surface is required. These tools have an extended working life compared to conventional embodiments.